To analyze the feasibility about diffusion bonding of Ti-6Al-4V alloy (represented by TC4 below) and type 25 low carbon steel (represented by 25-steel below), two kinds of experiments have been conducted by Gleeble-1500. One is directly diffusion bonding research of TC4 and 25-steel, the other is diffusion bonding of TC4 and 25-steel with adding Ni intermediate layer. The surface microstructures and the phase composition of bonding Joint have been systematic analysis through scanning electron microscope (SEM), energy spectrometer and XRD. Results indicated that the Ni intermediate layer largely improve the strength of joints observably, by suppressing the harmful diffusion between two sorts of based metal to avoid the appearance of harmful intermetallics in the joints.